/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.swak.boot.config.dubbo.event;

import static org.springframework.beans.factory.BeanFactoryUtils.beanNamesForTypeIncludingAncestors;
import static org.springframework.context.ConfigurableApplicationContext.ENVIRONMENT_BEAN_NAME;

import java.util.Objects;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.spring.context.annotation.EnableDubboConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.core.Ordered;
import org.springframework.core.env.Environment;

/**
 * The {@link ApplicationListener} class for Dubbo Config {@link BeanDefinition
 * Bean Definition} to resolve conflict
 * 
 * @see BeanDefinition
 * @see ApplicationListener
 * @since 2.7.5
 */
public class DubboConfigBeanDefinitionConflictApplicationListener
		implements ApplicationListener<ContextRefreshedEvent>, Ordered {

	private final Logger logger = LoggerFactory.getLogger(getClass());

	@Override
	public void onApplicationEvent(ContextRefreshedEvent event) {
		ApplicationContext applicationContext = event.getApplicationContext();
		BeanDefinitionRegistry registry = getBeanDefinitionRegistry(applicationContext);
		resolveUniqueApplicationConfigBean(registry, applicationContext);
	}

	private BeanDefinitionRegistry getBeanDefinitionRegistry(ApplicationContext applicationContext) {
		AutowireCapableBeanFactory beanFactory = applicationContext.getAutowireCapableBeanFactory();
		if (beanFactory instanceof BeanDefinitionRegistry) {
			return (BeanDefinitionRegistry) beanFactory;
		}
		throw new IllegalStateException("");
	}

	/**
	 * Resolve the unique {@link ApplicationConfig} Bean
	 * 
	 * @param registry    {@link BeanDefinitionRegistry} instance
	 * @param beanFactory {@link ConfigurableListableBeanFactory} instance
	 * @see EnableDubboConfig
	 */
	private void resolveUniqueApplicationConfigBean(BeanDefinitionRegistry registry, ListableBeanFactory beanFactory) {

		String[] beansNames = beanNamesForTypeIncludingAncestors(beanFactory, ApplicationConfig.class);

		if (beansNames.length < 2) { // If the number of ApplicationConfig beans is less than two, return
										// immediately.
			return;
		}

		Environment environment = beanFactory.getBean(ENVIRONMENT_BEAN_NAME, Environment.class);

		// Remove ApplicationConfig Beans that are configured by "dubbo.application.*"
		Stream.of(beansNames).filter(beansName -> isConfiguredApplicationConfigBeanName(environment, beansName))
				.forEach(registry::removeBeanDefinition);

		beansNames = beanNamesForTypeIncludingAncestors(beanFactory, ApplicationConfig.class);

		if (beansNames.length > 1) {
			throw new IllegalStateException(
					String.format("There are more than one instances of %s, whose bean definitions : %s",
							ApplicationConfig.class.getSimpleName(),
							Stream.of(beansNames).map(registry::getBeanDefinition).collect(Collectors.toList())));
		}
	}

	private boolean isConfiguredApplicationConfigBeanName(Environment environment, String beanName) {
		boolean removed = BeanFactoryUtils.isGeneratedBeanName(beanName)
				// Dubbo ApplicationConfig id as bean name
				|| Objects.equals(beanName, environment.getProperty("dubbo.application.id"));

		if (removed) {
			if (logger.isDebugEnabled()) {
				logger.debug("The {} bean [ name : {} ] has been removed!", ApplicationConfig.class.getSimpleName(),
						beanName);
			}
		}

		return removed;
	}

	@Override
	public int getOrder() {
		return LOWEST_PRECEDENCE;
	}
}
